Manually releasable grounding electrical plug



Jan. 25, 1966 MORSE MANUALLY RELEASABLE GROUNDING ELECTRICAL PLUGOriginal Filed July 13, 1962 United States Patent 3,231,844 MANUALLYRELEASABLE GROUNDING ELECTRICAL PLUG Milton Morse, 1 Horizon Road, FortLee, N.Y. Original application July 13, 1962, Ser. No. 209,579, nowPatent No. 3,178,667, dated Apr. 13, 1965. Divided and this applicationJune 26, 1964, Ser. No. 378,175 3 Claims. (Cl. 339-14) This applicationis a division of my copending application, Serial No. 209,579, filedJuly 13, 1962, and now Patent No. 3,178,667, issued April 13, 1965.

This invention relates generally to .the field of grounding electricalplugs of a type employing, in addition to the normally-present powerprongs, a grounding prong adapted to engage a separate portion of anelectric outlet receptacle. Devices of this type are generally known inthe art, and the invention lies in specific constructional details,permitting greater convenience in use together with a high degree ofsafety, and in a means for manufacturing the improved structure atreasonable cost.

While it is known in the art to provide a grounding blade which ispivotally mounted upon a plug body in such manner as to be deflectedupon the engagement of the plug with a non-grounded receptacle, so thatthe blade may establish a ground with respect to the cover plate of thereceptacle, such devices have not been entirely satisfactory and havefailed to obtain approval of certifying agencies. Where the pivotallymounted grounding prong or blade is only resiliently urged to a positionin which the same lies parallel to the power prongs, accidental contactof the fingers of the user, or other object, may readily deflect thesame from a parallel relation, wherein the grounding member will notenter the grounding opening of a grounded receptacle where suchreceptacle is not visible to the user. Further, where the groundingblade is only resiliently maintained in operative position, it can beaccidentally deflected to a degree wherein the power prongs may engagethe rec-eptacle without the grounding prong first establishing anelectrical ground, either with the grounding opening of the receptacleor the face plate, thereby subjecting the user to the possibility of asevere shock.

It is therefore among the principal objects of the present invention toprovide an improved grounding plug of the class described in which theabove-mentioned disadvantages have been substantially eliminated.

Another object of the invention lies in the provision of an improvedgrounding-type plug in which the grounding blade thereof may be heldrigidly in the grounding position by manually-operated mechanicallatching means.

Another object of the invention lies in the provision of an improvedgrounding-type plug of the class described in which the latching meansoperates automatically to lock the blade in grounding position uponbeing returned from a displaced position thereto by resilient means.

Another object of the invention lies in the provision of an improvedself-restoring grounding blade plug construction including afinger-operated mechanical latching means in which the manual release ofthe means serves to deflect the grounding blade through a small areonly, thereby assuring further deflection upon contact with the faceplate of a receptacle, and preventing entry of power prongs into thereceptacle prior to the establishment of a ground by the groundingblade.

Still another object of the invention lies in the provision of animproved grounding plug having a latched grounding blade, in which thelatching means is electrically insulated from the grounding blade as anadditional safety feature.

Yet another object of the invention lies in the provision of an improvedgrounding-type plug in which the 3,231,844 Patented Jan. 25, 1966grounding blade is provided with means for giving a clear indication tothe user if the grounding blade has not entered a grounding hole in areceptacle.

A further object of the invention lies in the provision of an improvedgrounding-type plug particularly adapted for use in conjunction withhand-held electrical tools and appliances, wherein the possibility ofshock to the user is greater than in the case of other appliances.

A further object of the invention lies in the provision of improvedmachine tool means for manufacturing a grounding electrical plugpossessed of the above advantages.

A feature of the invention lies in the fact that a single resilientcomponent may be employed to provide both grounding blade return andlocking function.

Another feature of the invention lies in the fact that the disclosedembodiments may be manufactured at least partially as tool machineoperations, thereby maintaining the cost of production at reasonablelevels, comparable with that of existing prior art devices.

These objects and features, as well as other incidental ends andadvantages, will more fully appear in the progress of the followingdisclosure, and be pointed out in the appended claims.

In the drawings, to which reference will be made in the specification,similar reference characters have been employed to designatecorresponding parts throughout the several views.

FIGURE 1 is an elevational view of a plug showing a first embodiment ofthe invention.

FIGURE 2 is a sectional view as seen from the plane 2-2 on FIGURE 1.

FIGURE 3 is a bottom plan view of a plug showing a second embodiment.

The body 311 at the rim 301 is provided with a notch 302 within whichthe element 314 may swing about its pivotal connection 303 to the body311. The pivotal connection 303 may be substantially the same as thatshown in FIGURE 24, wherein the element 314 is normally urged to aposition parallel to the blade 313 by a spring 306.

The lower end of the body 311 (as viewed in FIG. 1) is provided with aninsulating closure 304 preferably in the form of a perforated fiber discupon the upper surface of which is mounted a lever 305 pivotallyconnected by a hollow rivet 307. The lever 305 acts as a movablelatching and deflecting means which at the latching portion thereof hasa hook 308 and opposite the element 314 has a deflecting portion 309,the handle portion projecting outward of the rim 301 through a recess302a. As shown in the full lines in FIGURE 2, deflection of the element314 is arrested by hook 308. When it is desired to deflect the blade,the handle portion of lever 305 is shifted to the left (clockwise inFIGURE 2) to its dot-dash line position, which pulls hook 308 out of theway .and partially deflects element 314 by contact at portion 309. Theremainder of the shifting of element 314 is accomplished by itsengagement with the face plate of the electrical receptacle (not shown).Upon removal of the plug 310 from said receptacle, the spring 306 pullsit back to the original full line position shown in FIGURES 1 and 2.

Turning to the fourth embodiment, again certain of the parts are givensimilar reference characters with the prefix 4. Plug 410 issubstantially identical with plug 310 except that the movable latchingand deflecting means (lever 305) is absent with a loss of its function.Deflection of the element 414 is obtained manually, the element 414,when shifted, being angularly disposed with respect to a plane passingthrough the pair of blades 412 and 413 as it pivots about the connector403 which may take the form of a rivet in an upstanding lug bearing403a.

I 'wish it to be understood that I do not consider the invention limitedto the precise details of structure shown and set forth in thisspecification, for obvious modifications will occur to those skilled inthe art to which the invention pertains.

I claim:

1. Grounding electrical plug construction comprising: a plug body, apower blade projecting from said body, a movable grounding element inits regular position being spaced and parallel with respect to saidpower blade and in another position angularly deflected with respect toits regular position; movable latching and deflecting means in thelatching position thereof obstructing movement of said grounding elementand in a shifted position thereof unlatching and shifting said groundingelement from the regular position thereof to another position.

2. Grounding electrical plug construction comprising: a plug body, apower blade projecting from said body, a movable grounding element inits regular position being spaced and parallel with respect to saidpower blade and in another position angularly deflected with respect toits regular position; a spring urging the grounding element to itsregular position; movable latching and deflecting means in the latchingposition thereof obstructing movement of said grounding element and in ashifted position thereof unlatching and shifting said grounding elementfrom the regular position thereof to another position.

3. Grounding electrical plug construction comprising: a plug body, apower blade projecting from said body, a movable grounding element inits regular position being spaced and parallel with respect to saidpower blade and in another position angularly deflected with respect toits regular position; movable latching and deflecting means including ahooked lever in the latching position thereof obstructing movement ofsaid grounding element and in a shifted position thereof unlatching andshifting said grounding element from the regular position thereof toanother position.

References Cited by the Examiner UNITED STATES PATENTS 2,922,134 1/1960Elfenbein 339-14 FOREIGN PATENTS 326,324 12/ 1957 Switzerland.

ALBERT H. KAMPE, Primary Examiner.

PATRICK A. CLIFFORD, Examiner.

1. GROUNDING ELECTRICAL PLUG CONSTRUCTION COMPRISING: A PLUG BODY, APOWER BLADE PROJECTING FROM SAID BODY, A MOVABLE GROUNDING ELEMENT INITS REGULAR POSITION BEING SPACED AND PARALLEL WITH RESPECT TO SAIDPOWER BLADE AND IN ANOTHER POSITION ANGULARLY DEFLECTED WITH RESPECT TOIT REGULAR POSITION; MOVABLE LATCHING AND DEFLECTING MEANS IN THELATCHING POSITION THEREOF OBSTRUCTING MOVEMENT OF SAID GROUNDING ELEMENTAND IN A SHIFTED POSITION THEREOF UNLATCHING AND SHIFTING SAID GROUNDINGELEMENT FROM THE REGULAR POSITION THEREOF TO ANOTHER POSITION.